NDI opacity on channel randomly does not work

Hello peeps!

Setting opacity on NDI channel:
_Caspar.Execute(String.Format("MIXER " & channel.ToString & "-" & layer.ToString & " " & "OPACITY " & opacity_value & " " & duration & " " & transition))

time to time does not make any effect.
So output on the consumer does not either appear or disappear.
Adding a further screen consumer on the same channel fix the behaviour.
Any one experienced the same?

Has outputed NDI from CasparCG to vMix on a almost daily bases for 2 years without any problem with alpha in NDI.
CasparCG is 2.3.3, vmix v26, sourcematerial HTML-templates (raw code and some done with Loopic) and PNG:s

Maybe it should read opacity_value.ToString. What is the datatype and value of that opacity_value variable?

As I’ve been working with NDI a lot lately, with CasparCG, vMix, OBS, NDI tools, NDI connect etc, I’ve noticed many times lag on NDI which was highly dependent on hardware I’ve been using, but none of them were CasparCG issue. As the command you’re using though is CasparCG MIXER and has nothing to do with NDI output, did you check that your NDI receiver is not showing any freeze frame in order to be able to see the change to the opacity?